1. Field of the Invention
Germicidal soap bars of the conventional opaque milled type are well known. Attempts however to extend the field of germicidal bars to germicidal transparent bars by a process of adding powdered germicide at the chip-mixing step have been unsuccessful, resulting in opaque bars, particularly at the more useful levels, e.g., above about 1%, or when the proportion of germicide is low, e.g., about 0.15%, in specks of undispersed germicide in an otherwise transparent bar. This property of insolubility in a soap mass during processing to a transparent state is shared by the well-known phenolic germicides heretofore disclosed as useful in the conventional milled soap bars, for example, 2,2'methylenebis(3,4,6-trichlorophenol), 2,4,4'-trichlorocarbanilide, and 3,4',5-tribromosalicylanilide and the 4',5 -analogue thereof, as well as 2,4,4'-trichloro-2'-hydroxy diphenyl ether.
2. Description of the Prior Art
Various methods are known for the manufacture of transparent soaps. For example transparent soaps may be made by the old and well-known cold process technique. By this method, tallow, coconut, and castor oil, and sometimes rosin, in the melted state are place in a vessel and stirred with a calculated quantity of sodium hydroxide solution in the presence of alcohol, glycerine, or sugar, or mixtures of these. The resulting soap is allowed to stand for some time whereupon saponification is complete and the soap is transparent.
In another method well known in the art, sodium soap of the desired fat formula is dried and shredded, and the shreds are dissolved in alcohol. Alternatively, the fats may be treated with alcoholic caustic soda. Insoluble matter, such as sodium carbonate, is separated from the resulting soap solution, the bulk of the alcohol is distilled off, and the gelatinous residue run into molds. Upon standing, the soap loses some of the alcohol and becomes transparent, especially if stored at about 35.degree.C.
Methods for making transparent soap are set forth in U.S. Pat. No. 2,970,116, and in the Lewkowitsch text "Chemical Technology and Analysis of Oils, Fats and Waxes", 6th Ed., Vol. III, (Macmillan), pages 216, 343, and 346. In U.S. Pat. No. 1,475,663 there is described in detail a method for making transparent soap involving the addition of alcohol to dissolve the soap, and the subsequent removal of the alcohol by distillation.
British Pat. No. 963,907 describes the enhancement of the antibacterial action of phenolic germicides and certain polyamines.
British Pat. No. 1,227,959 discloses the anti-bacterial activity of a germicide in a soap bar is enhanced if the germicide is first dissolved in one or more of a variety of solvents. The process is stated to be applicable to a translucent bar.
U.S. Pat. No. 3,155,624 discloses a superfatted transparent bar containing a fatty acid and a polyhydric alcohol. The transparency is obtained by the process described in the above-mentioned U.S. Pat. No. 2,970,116.
U.S. Pat. No. 3,485,919 discloses that a variety of alkylphenols promote the antibacterial activity of some of the commonly used antibacterial agents.
U.S. Pat. No. 3,594,322 discloses the presolubilization of brominated salicylanilides in an alkaline solvent such as an alkanolamide, and incorporation of the solution into a liquid detergent composition.
In "Soap and Chemical Specialties", pages 47-50 and 116-122, January, 1968, an article by T. E. Furia and A. G. Schenkel describes the characteristics and properties of 2,4,4'-trichloro-2'-hydroxy diphenyl ether.